Self-standing GaN substrate, GaN crystal, method for producing GaN single crystal, and method for producing semiconductor device

1. A self-standing GaN substrate with an angle between the normal of the principal surface and an in-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when a region excluding a portion at a distance of 2 mm or less from a substrate end surface, of the principal surface, is assumed to be an effective region, a stacking fault density obtained by dividing a total length of stacking faults existing in the effective region by an area of the effective region is less than 15 cm −1 .

2. The self-standing GaN substrate according to claim 1 , wherein the size of the projected image is a 10 mm square or more.

3. The self-standing GaN substrate according to claim 1 , wherein the size of the projected image in a c-axis direction is 15 mm or more.

4. The self-standing GaN substrate according to claim 1 , wherein the size of the projected image in an a-axis direction is 25 mm or more.

5. The self-standing GaN substrate according to claim 1 , wherein the self-standing GaN substrate contains fluorine.

6. The self-standing GaN substrate according to claim 5 , wherein a concentration of fluorine exceeds 1×10 15 cm −3 .

7. The self-standing GaN substrate according to claim 1 , wherein the self-standing GaN substrate contains a stacking fault.

8. The self-standing GaN substrate according to claim 1 , wherein the stacking fault density is less than 5 cm −1 .

9. The self-standing GaN substrate according to claim 8 , wherein the stacking fault density is less than 1 cm −1 .

10. The self-standing GaN substrate according to claim 1 , wherein a dislocation density obtained by dividing a total number of dislocations existing in the effective region by an area of the effective region is less than 4×10 5 cm −2 .

11. The self-standing GaN substrate according to claim 10 , wherein the dislocation density is less than 1×10 5 cm −2 .

12. The self-standing GaN substrate according to claim 11 , wherein the dislocation density is less than 4×10 4 cm −2 .

13. A manufacturing method of a GaN single crystal, the method comprising: preparing the self-standing GaN substrate according to claim 1 ; and epitaxially growing GaN on the self-standing GaN substrate.

14. A manufacturing method of a GaN single crystal, the method comprising: growing a first GaN crystal using the self-standing GaN substrate according to claim 1 as a seed; and subsequently, growing a second GaN crystal using a part of or all of the first GaN crystal as a seed.

15. The manufacturing method according to claim 13 , wherein the manufacturing method is a manufacturing method of a bulk GaN single crystal.

16. A manufacturing method of a semiconductor device, the method comprising: preparing the self-standing GaN substrate according to claim 1 ; and forming a device structure by epitaxially growing one or more types of nitride semiconductors on the self-standing GaN substrate.

17. A manufacturing method of a GaN layer-bonded substrate, method comprising: implanting ions in a vicinity of the principal surface of the self-standing GaN substrate according to claim 1 ; bonding the principal surface side of the self-standing GaN substrate to a hetero-composition substrate; and forming a GaN layer bonded to the hetero-composition substrate by separating the self-standing GaN substrate at the ion-implanted region as a boundary.

18. A GaN layer-bonded substrate with a structure in which a GaN layer separated from the self-standing GaN substrate according to claim 1 is bonded to a hetero-composition substrate.